Shelf



FIG. 1 is a perspective view of a shelf showing my new design; and

FIG. 2 is a front plan view thereof; and

FIG. 3 is a rear plan view thereof; and

FIG. 4 is a right-side view thereof; and

FIG. 5 is left-side view thereof; and

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings depict portions of the shelf that form no part of the claim. 

CLAIM The ornamental design for a shelf, as shown and described. 